#!/usr/bin/perl

# Simple modeline-to-fb.modes translator
# (c) 1998 by Patrick Reynolds
# distributed under the GNU General Public License
 
# mapping of modeline options to fb.modes options
%options_map = (
  "-hsync" => "hsync low",
  "-vsync" => "vsync low",
  "+hsync" => "hsync high",
  "+vsync" => "vsync high",
  "interlace" => "laced true",
  "doublescan" => "double true"
);

@possible_vxres = ( 640, 800, 1024, 1152, 1280, 1600, 1920, 2048 );

# default settings (override with -d and -r)
$depth = 8;
$rounding = 128;

# parse options
while ($ARGV[0] =~ /^-/) {
  $arg = shift;
  if ($arg eq "-d" || $arg eq "--depth") {
    if (!($arg = shift @ARGV)) {
      usage("-d requires an argument");
    }
    $depth = $arg;
  }
  elsif ($arg eq "-r" || $arg eq "--rounding") {
    if (!($arg = shift @ARGV)) {
      usage("-r requires an argument");
    }
    $rounding = $arg;
  }
  elsif ($arg eq "-x" || $arg eq "--vxres") {
    if (!($arg = shift @ARGV)) {
      usage("-x requires an argument");
    }
    push @possible_vxres, (split/,/,$arg);
    @possible_vxres = sort { $a <=> $b } @possible_vxres;
    print "new vxres: " . (join ",", @possible_vxres) . "\n";
  }
  elsif ($arg eq "-h" || $arg eq "--help") {
    usage();
  }
  else {
    usage("unknown option: $arg");
  }
}

# find out how much video memory is available
open(FBSET, "fbset -i|") || die "could not detect available video memory";
while (<FBSET>) {
  if (/Size\s*:\s*(\d+)/) {
    $size = $1;
    last;
  }
}
if (!$size) { die "could not detect available video memory"; }

# huge kludge (hey, that rhymes!) ...
#   subtract 16384 from the available memory $size
#   why?  the default 640x480 mode uses all but 16384, and when I set it
#   to use more than that, it oopses (!).  So... for safety's sake, and
#   because you probably don't use those 15-25 lines anyway...
$size -= 16384;

print "# modes.fb - video mode descriptions for fbset
#
# See fbset(8) and fb.modes(5) for more information

";

$flag = 0;
# read all XF86Config files
while(<>) {
  chomp;
  next if !(($name, $clock, $xres, $xsyncstart, $xsyncend, $xfres,
                  $yres, $ysyncstart, $ysyncend, $yfres, $extra) =
    /^\s*modeline\s+"([^"]+)"\s+([0-9.]+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s*(.*)$/i);
  $flag = 1;

  # timing transformations, as described in the fb HOWTO
  $pixtime = int(1000000/$clock);
  $left = $xfres - $xsyncend;
  $right = $xsyncstart - $xres;
  $hsynclen = $xsyncend - $xsyncstart;
  $top = $yfres - $ysyncend;
  $bottom = $ysyncstart - $yres;
  $vsynclen = $ysyncend - $ysyncstart;

  # pick a virtual X and Y resolution
  $vxres = get_vxres($xres);
  if ($vxres < 0) {
    print STDERR "Could not guess a good virtual resolution for mode $name.\n";
    print STDERR "Use the advanced options --rounding and --vxres.\n";
    next;
  }
  $vyres = int($size/$vxres);

  # print out our entry
  print "mode \"$name\"\n";
  print "  geometry   $xres $yres   $vxres $vyres   $depth\n";
  print "  timings    $pixtime   $left $right   $top $bottom   $hsynclen $vsynclen\n";

  # handle extra options at the end of the modeline
  $extra =~ tr/A-Z/a-z/;
  @options = split/\s+/,$extra;
  foreach (@options) {
    if ($options_map{$_}) {
      print "  $options_map{$_}\n";
    }
    else {
      print "  # unknown option: $_\n";
    }
  }
  print "endmode\n\n";
}

if (!$flag) {
  print STDERR "No modelines found.\n";
  print STDERR "Make sure the file you specified was an XF86Config file and\n";
  print STDERR "used the single-line Modeline format.\n\n";
  print STDERR "Use \"$0 --help\" for help.\n";
}

sub get_vxres {
  foreach (@possible_vxres) {
    return $_ if ($_ >= $_[0] && ($_ % $rounding) == 0);
  }
  return -1;
}

sub usage {
  print STDERR "$_[0]\n" if ($_[0]);
  print STDERR "$0 [OPTION] [FILES]\n\n";
  print STDERR "  -d,--depth depth     use a certain display depth (default is 8)\n";
  print STDERR "  -h,--help            what you see here\n\n";
  print STDERR "Advanced options:\n";
  print STDERR "  -r,--rounding div    vxres divisor (default is 128)\n";
  print STDERR "  -x,--vxres X,X,X,... extra possible vxres values\n\n";
  print STDERR "[FILES] refers to one or more XF86Config files.  Note that\n";
  print STDERR "all modelines must be in single-line format.\n\n";
  print STDERR "Example:\n";
  print STDERR "  $0 -d 16 /etc/X11/XF86Config\n";
  exit 0;
}